Primordial nucleosynthesis is reexamined in the context of a detailed comparison of theory and observation. A new argument is presented to show how the observed abundances of D and ³He can be used to derive a lower bound to the nucleon density. The authors define a conservative range for the nucleon-to-photon ratio: η = (3 - 10)×10⁻¹⁰. New observations of ⁷Li are consistent with the abundances of D and ³He and help to define a reasonable range: η = (4 - 7)×10⁻¹⁰. In either of these ranges the predicted and observed abundances of D, ³He, and ⁷Li are all in concordance. The upper bounds correspond to ΩN ≤ 0.14 - 0.19, and it is concluded that nucleons fail to close the universe by at least a factor of 5 - 7. The authors review the recent observational data on ⁴He and conclude that there is complete consistency between the predicted abundance of ⁴He and those of the other light elements.
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Yang et al. (1984) studied this question.